Aedes triseriatus is a tree hole-breeding mosquito that is a vector of LaCrosse encephalitis virus. Ae. triseriatus larvae appear to experience density dependent growth and development in natural and artificial containers, suggesting that resource limitation and intraspecific competition may be important for this species. There has, however, been recent controversy over the importance of one type of resource (leaf litter) as a limiting resource in tree holes. Ae. aegypti and Ae. albopictus co-occur in containers with Ae. triseriatus in Florida, primarily in artificial containers. In laboratory studies, both of these species appear to be competitively superior to Ae. triseriatus. Ae. albopictus seems to be a particularly effective competitor, as this recently introduced species has spread rapidly into environments occupied by Ae. triseriatus and Ae. aegypti. The precise effects of resource limitation, intraspecific, and interspecific competition on populations of container Aedes have proved difficult to determine because direct manipulations of tree holes is difficult, and because containers at any given site vary greatly in physical and biotic conditions. There is a need for controlled experiments in natural and man made containers testing the importance of resource limitation and competition. During this proposed project, field experiments employing a block design within tree holes and tires will be used to test for the effects of resource limitation, intraspecific, and interspecific competition on survivorship, size, development rate, and cohort rate of increase in these three Aedes species. Field experiments in tires in Florida will test for competitive asymmetries among three species, and whether the presence vs. absence of leaf litter affects competition in tires. A field experiment in natural tree holes and tires in Illinois will test whether predation on first instar Ae. triseriatus by Anopheles barberi can increase cohort rate of increase of Ae. triseriatus by reducing intraspecific competition. Another field experiment in tires and tree holes in Illinois will test whether early cohorts of Ae. triseriatus have carryover effects on leaf litter that influence performance of later, nonoverlapping cohorts of Ae. triseriatus, and whether drying of leaf litter affects its quality as a food resource. Finally, a field experiment in tires and tree holes will establish the quantitative relationship between leaf litter abundance and cohort growth rate.